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pythonjsonapi-design

How to Return Nested Values from Complicated JSON API

I am setting up a weather camera which will provide a live stream of the current conditions outside, but I also would like to overlay continuously updated weather conditions (temperature, wind speed/direction, current weather) from a local National Weather Service weather station, from a browser API source provided in JSON format.

I have had success extracting the desired values from a different API source using a Python script I wrote; however long story short that API source is unreliable. Therefore I am using API from the official National Weather Service ASOS station at my nearby airport. The output from the new API source I am polling from is rather complicated, however, with various tiers of indentation. I have not worked with Python very long and tutorials and guides online have either been for other languages (Java or C++ mostly) or have not worked for my specific case.

First off, here is the structure of the JSON that I am receiving:

screenshot of JSON structure

I underlined the values I am trying to extract. They are listed under the OBSERVATIONS section, associated with precip_accum_24_hour_value_1, wind_gust_value_1, wind_cardinal_direction_value_1d, and so on. The issue is there are two values underneath each observation so the script I have tried isn't returning the values I want. Here is the code I have tried:

import urllib.request
import json

f = urllib.request.urlopen('https://api.synopticdata.com/v2/stations/latest?token=8c96805fbf854373bc4b492bb3439a67&stid=KSTC&complete=1&units=english&output=json')

json_string = f.read()
parsed_json = json.loads(json_string)

for each in parsed_json['STATION']:
    observations = each['OBSERVATIONS']

print(observations)

This prints out everything underneath the OBSERVATIONS in the JSON as expected, as one long string. 

{'precip_accum_24_hour_value_1': {'date_time': '2018-12-06T11:53:00Z', 'value': 0.01}, 'wind_gust_value_1': {'date_time': '2018-12-12T01:35:00Z', 'value': 14.0},

to show a small snippet of the output I am receiving. I was hoping I could individually extract the values I want from this string, but everything I have attempted is not working. I would really appreciate some guidance for finishing this piece of code so I can return the values I am looking for. I realize it may be some kind of loop or special syntax.

Solution

  • Try something like this:

    for each in parsed_json['STATION']:
    observations = each['OBSERVATIONS']
    for k, v in observations.items():
        print(k, v["value"])

    JSON maps well into python's dictionary and list types, so accessing substructures can be done with a[<index-or-key>] syntax. Iteration over key-value pairs of a dictionary can be done as I've shown above. If you're not familiar with dictionaries in python yet, I'd recommend reading about them. Searching online should yield a lot of good tutorials.

    Does this help?